1. Field of the Invention
The present invention relates to a key top used as a pushbutton switch for various mobile communication devices such as a mobile phone and an automobile telephone, a remote control, or car-mounted electronic equipment.
2. Description of the Related Art
As a material for a key top for a pushbutton switch of various mobile communication devices and electronic equipment, such as a mobile phone and a remote control, resins are mainly used for reasons such as a satisfactory sensation of an operation and rich design variations. In terms of enhancement of design, there is a demand for a sensation of a metal-type material with lustrousness of metal (in the present specification, referred to as a xe2x80x9csensation of metalxe2x80x9d) and illumination of a display portion displaying a letter, a symbol, or the like.
In order to satisfy the above-mentioned demand, in the case of providing a sensation of metal to a key top by utilizing a resin material, a key top made of a resin is produced by a following method in which a metal layer is formed in a desired position of the surface of a key top made of a resin by vapor deposition or sputtering (first prior art) or a method in which a resin to be plated with metal and a resin that is not to be plated with metal are subjected to coinjection molding, whereby a plating layer is provided on the resin to be plated with metal (second prior art).
Alternatively, a key top made of a resin has also been produced by a method in which a coating with a sensation of metal is applied (third prior art) or a method in which an electroplating layer formed on the surface of a resin to be plated with metal is etched with a laser to form a letter, a symbol, or the like (fourth prior art).
However, according to the method of the first prior art, the metal layer formed by vapor deposition or sputtering is thin. Therefore, when a key top made of a resin is repeatedly pressed down, the metal layer wears away and may eventually disappear. In order to solve this problem, the surface of the metal layer is coated with a protective layer, the metal layer is formed on the reverse surface of a flat resin film, and the resultant film is curved along the surface of a key top made of a resin to be integrated with a key top body, and the like. According to the former method, dust is likely to adhere during coating. According to the latter method, the metal layer is likely to be cracked when the resin film is curved. In both methods, the yield is poor and the cost is high.
According to the method of the second prior art, the display portion is designed by coinjection molding. Therefore, a display portion with minute and complicated designs cannot be realized and the cost is high.
According to the method of the third prior art, compared with the case where the metal layer is formed by plating, it is difficult to provide a smooth mirror surface, and wear resistance is not satisfactory. According to the method of the fourth prior art, unless a laser treatment is conducted after plating, it is difficult to form, in particular, letters containing an island portion isolated from the periphery, such as digits xe2x80x9c9xe2x80x9d and xe2x80x9c0xe2x80x9d, and it is difficult to adjust a laser output for forming a display portion without influencing regions on the periphery of a letter, a symbol, or the like.
Jp 2000-207985 A describes a method of producing a key top by coating a desired site with a conductive ink, and plating the site coated with the conductive ink. However, according to this method, in order to decrease a resistance of the conductive ink, it is required to use silver powder or copper powder, which makes the conductive ink expensive, resulting in a high cost.
Therefore, with the foregoing in mind, it is an object of the present invention to provide a key top for a pushbutton switch having a sensation of metal, a rich design, a satisfactory yield, a low cost, the capability of being illuminated, and excellent durability.
In order to achieve the above-mentioned object, according to the present invention, a key top for a pushbutton switch in which a base layer made of an insulating resin that can be plated with metal and an electroless plating layer formed on the surface of the base layer are stacked on a key top body is provided.
In the key top for a pushbutton switch, the base layer made of an insulating resin that can be plated with metal is formed on a surface of the key top body, and the electroless plating layer is formed on a surface of the base layer. Therefore, the plating layer can be provided directly and easily on the insulating resin. As a result, a key top for a pushbutton switch can be obtained, which has a sensation of metal while using a resinous key top body, rich design, a satisfactory yield, and a low cost.
Furthermore, according to the present invention, there is provided a key top for a pushbutton switch in which a polymer coating layer is formed on the surface of the base layer, wherein the electroless plating layer is formed on the surface of the base layer where the polymer coating layer is not formed.
The electroless plating layer is formed on the surface of the base layer where the polymer coating layer is not formed. Therefore, a display portion, a pattern, and the like can be formed by the electroless plating layer and the polymer coating layer. As a result, a key top for a pushbutton switch having an improved design can be obtained. Furthermore, the periphery of the electroless plating layer is in contact with the polymer coating layer, so that the ends of the electroless plating layer can be protected by the polymer coating layer, and wear and a loss of the electroless plating layer can be prevented. Furthermore, during production, the polymer coating layer functions as a masking layer for a region where the electroless plating layer is not formed, so that the electroless plating layer can be easily attached to a desired place. As a result, a key top for a pushbutton switch that has the capability of being mass-produced at a low cost can be obtained.
Furthermore, according to the present invention, a key top for a pushbutton switch having an electroplating layer further formed by electroplating on the electroless plating layer is provided.
When the electroplating layer further formed by electroplating is provided on the electroless plating layer, a key top for a pushbutton switch can be obtained, which has enhanced wear resistance, lustrousness, and a sensation of metal.
Furthermore, according to the present invention, a key top for a pushbutton switch in which a polymer coating layer is further provided on the surface of the electroless plating layer or the electroplating layer is provided.
When the polymer coating layer is further provided on the surface of the electroless plating layer or the electroplating layer, these plating layers are protected by the polymer coating layer. Thus, wear and a loss of the plating layer can be prevented, and as a result, a key top for a pushbutton switch having enhanced wear resistance can be obtained. More specifically, even if the key top is pressed down repeatedly, the plating layer is unlikely to peel off. Furthermore, coloring that is not present on the key top body can be provided to the surface of the key top. For example, if the polymer coating layer is formed as a colored transparent layer, light reflected from the plating layer comes in the eyes of a human through the colored transparent polymer coating. Therefore, the key top surface having coloring that cannot be obtained only with the plating layer can be formed, which enables the design to be richer. In particular, even if a part of the plating layer forms a display portion of a letter, a symbol, or the like, the letter, the symbol, or the like does not peel off. Thus, a key top surface having enhanced durability with an enhanced design can be obtained.
According to the present invention, there is provided a key top for a pushbutton switch in which the polymer coating layer and the plating layer are formed so as to be visually recognized.
In the key top for a pushbutton switch, the plating layers including the electroless plating layer and the electroplating layer, and the polymer coating layer can directly form a display portion, and a key top surface with durability and coloring that cannot be obtained by vapor deposition or sputtering can be obtained. Furthermore, a key top for a pushbutton switch can be obtained, which has an enhanced design provided with a sensation of metal due to the difference in color between the polymer coating layer and the plating layers.
According to the present invention, a key top for a pushbutton switch in which a key top body comprises a resin film and a resin base that are integrated with each other is provided.
In the key top for a pushbutton switch in which the key top body comprises the resin film and the resin base that are integrated with each other, a flat resin film can be coated with the base layer and the polymer coating layer, and a coating operation of the base layer and the like is easy. Thus, a key top for a pushbutton switch can be obtained at a low cost.
Furthermore, according to the present invention, a key top for a pushbutton switch that may be illuminated is provided, in which the key top body is made of a transparent resin, and the transmittance of visible light of the base layer is in the range from 3% to 95%.
When the key top body is made of a transparent resin and the transmittance of visible light of the base layer is in the range from 3% to 95%, a key top for a pushbutton switch having a sensation of metal and an improved design, and that is capable of being pressed without fail even at night or in a dark place can be obtained.
Furthermore, in order to achieve the above-mentioned object, according to the present invention, a method of producing a key top for a pushbutton switch, in which the surface of a key top body is coated with a liquid resin to form an insulating base layer to be plated with metal, and then an electroless plating layer is formed on the surface of the base layer by electroless plating is provided.
According to the above-mentioned production method, the plating layer can be provided directly and easily on the insulating base layer, and minute and complicated designs can be provided on a key top. Thus, a key top having a desirable appearance and enhanced design can be produced. In particular, compared with the case where electroplating is provided, operation processes can be shortened, and a key top for a pushbutton switch with a sensation of metal can be produced at a low cost. Furthermore, the electroless plating layer can be made thicker to some degree. Therefore, a key top for a pushbutton switch having enhanced durability and design can be obtained.
Furthermore, according to the present invention, a method of producing a key top for a pushbutton switch, in which a part of the surface of the base layer is coated with polymer coating ink to form a polymer coating layer, and an electroless plating layer is formed on the surface of the base layer where the polymer coating layer is not formed by electroless plating is provided.
According to the above method, the polymer coating layer is previously formed on the surface of the base layer before the electroless plating layer is formed, so that the polymer coating layer is not plated. Therefore, two layers, a layer to be plated and a layer that is not to be plated, can be easily formed on the surface of a key top. Thus, a key top for a pushbutton switch, in which a display portion is formed easily and which is excellent in variation of design, can be easily provided.
According to the present invention, a method of producing a key top for a pushbutton switch in which an electroplating layer is further stacked on the electroless plating layer by electroplating is provided.
According to the above production method, the electroless plating layer becomes a base layer for attaching an electroplating, and the electroplating layer can be provided easily. Therefore, a key top having enhanced durability and a sensation of metal can be produced at a low cost. Furthermore, the electroless plating layer can previously form a letter, a symbol, or the like that may become a display portion or the like; therefore, it is not required to conduct a laser treatment in a later process. Furthermore, electroplating can plate Cr (chromium) and Au (gold), which are difficult to be attached by electroless plating. Therefore, a key top for a pushbutton switch having enhanced wear resistance and strength and a key top for a pushbutton switch rich in design variation can be obtained.
According to the present invention, a method of producing a key top for a pushbutton switch, in which a polymer coating layer is further formed on the surface of the electroless plating layer or the electroplating layer is provided.
When the polymer coating layer is provided on the surface of the electroless plating layer or the electroplating layer, these plating layers are protected by the polymer coating layer. Therefore, a key top for a pushbutton switch having enhanced wear resistance can be produced. Furthermore, the plating layer can be easily coated with the polymer coating layer, using a colored transparent liquid resin. Thus, a key top for a pushbutton switch having coloring that cannot be obtained only with the plating layer and having an improved design can be produced at a low cost.
Furthermore, according to the present invention, a method of producing a key top for a pushbutton switch including the step of forming a base layer and further a polymer coating layer on a resin film to be a part of a key top body to curve the resin film is provided.
According to the above production method, the base layer and the polymer coating layer are formed on the flat resin film, so that it becomes easy to apply these layers. In particular, even when the base layer or the polymer coating layer are previously applied so as to have a shape such as a letter and a pattern or a complicated design, they are printed onto the flat resin film. Therefore, a key top for a pushbutton switch being having an improved design can be easily produced.
Furthermore, according to the present invention, a method of producing a key top for a pushbutton switch, in which the base layer has a transmittance of visible light of in the range from 3% to 95% is provided.
When the base layer having the transmittance of visible light from 3% to 95% is formed, light is hardly blocked by the base layer. Thus, a key top for a pushbutton switch that may be illuminated can be obtained, in which light transmitted through the base layer illuminates the key top.
According to the present invention, a method of producing a key top for a pushbutton switch, in which an electroless plating layer has a transmittance of visible light in the range from 0.1% to 80% is provided.
When the electroless plating layer having the transmittance of visible light from 0.1% to 80% is formed, light is hardly blocked by the electroless plating layer. Thus, a key top for a pushbutton switch that may be illuminated can be obtained, in which light transmitted through the electroless plating layer. Furthermore, by varying the transmittance of visible light, the color of a metal texture can be changed, and thus, a key top for a pushbutton switch rich in design can be produced.
According to the present invention, a method of producing a key top for a pushbutton switch, in which the key top body is made of a transparent resin, and the base layer has a transmittance of visible light in the range from 3% to 95% is provided.
When the key top body is made of the transparent resin and the base layer has a transmittance of visible light from 3% to 95%, a key top for a pushbutton switch that may be illuminated can be obtained.
The contents of the present invention are not limited to the above-mentioned description. The object, advantage, feature, and use of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures. It should be understood that various appropriate modifications without departing from the scope and spirit of this invention are contained in the scope of the invention.